Effects of Mercury on Anaerobic Granular Sludge Activity

In order to understand the toxicity of mercury on the activity of anaerobic granular sludge, the inhibition and rejuvenation effects of mercury ion (Hg²⁺) on methanogenic production activity of the anaerobic granular sludge was investigated using Smith fermentation method under laboratory condition. The results showed that the Hg²⁺ had quantitative effect on inhibition of methanogenic production activity of the anaerobic granular sludge. The higher the Hg²⁺ concentration was, the greater of the inhibition capacity it had. When the Hg²⁺ concentration was less than 50 mg/l, the activity of anaerobic granular sludge could be easily resumed. However, if the concentration was 100 mg/l, the activity could be mostly resumed. When the concentration was 300 mg/l, the Hg²⁺ would make an irreversible toxic inhibition on the anaerobic granular sludge. Our results indicated that the anaerobic granular sludge activity was tolerant to Hg²⁺ up to a concentration of 50 mg/l. Analysis of the amount of coenzyme F₄₂₀ and extracellular polymeric substances (EPS) of anaerobic granular sludge in different Hg²⁺ concentrations revealed that Hg²⁺ had conspicuous effects on the contents of coenzyme F₄₂₀ and EPS in anaerobic granular sludge. High Hg²⁺ concentration would cause substantially decline in coenzyme F₄₂₀ and EPS.